Integrated electro-optic package for reflective spatial light modulators

ABSTRACT

An array of reflective LCSLM pixels formed on a substrate with a light polarizing layer positioned in overlying relationship to the array. A light source mounted in an optically clear support positioned in overlying relationship to and spaced from the array, so that light evenly illuminates the array through the support and allows passage of reflected light from the array back through the support. Electrical connections are made from the array, through leads in the support and to external contacts. A diffuser mounted in overlying and spaced relationship to the support to form an image plane for reflected light from the array.

FIELD OF THE INVENTION

The present invention pertains to reflective spatial light modulatorsand more specifically to packaging and illumination of reflectivespatial light modulator devices.

BACKGROUND OF THE INVENTION

Liquid crystal spatial light modulators (LCSLMs) are very popular at thepresent time and are utilized in a great variety of direct view typedisplays, such as digital watches, telephones, lap-top computers and thelike. In general, liquid crystal devices are illuminated with arelatively large, separately mounted light source, preferably from therear (back-lighting), so that most of the light travels directly throughthe liquid crystal and outwardly to the eye of a viewer. Direct viewdisplays require a substantial amount of light for suitable viewing,generally about 25 fL to be visible in office environments and more than100 fL to be visible in an outdoor environment. To provide this amountof light or luminance at the outlets of the LCSLMs requires a relativelybright, and large, light source.

Further, LCSLMs used in display applications require polarized light anda diffuser placed in the optical path. Light entering the LCSLMs must bepolarized, and an analyzing polarizer must be placed in the path ofexiting light to differentiate between which LCSLM pixels are ON andwhich are OFF. A diffuse element, either near the modulating LCSLM or asa screen in a projection system, must be used. Generally, the result isto produce a relatively large and cumbersome package, usually withseveral discrete components.

This problem severely limits the usefulness of liquid crystal displays.For example, in portable electronic devices such as telephones, two-wayradios, pagers, etc. the displays are limited to a few alpha-numericdigits. Generally, if a small portable device is desired, the displaymust be reduced to a very small number of digits, since the size of thedisplay dictates the minimum size of the device into which it isintegrated.

One way to alleviate package size problems is to use a very small liquidcrystal spatial light modulator (LCSLM) as the image source, with amagnifying optical system. This can take the form of a projectiondisplay, in which light modulated by the liquid crystal is projected bythe optical system onto a diffusing screen, or it can take the form of avirtual display, where the optical system creates a large virtual imageof the small real image created by the LCSLM.

By using the LCSLM in a reflective mode, a reflective LCSLM is formed,which can be built onto a silicon substrate that contains the drivecircuitry and other related electronics. When using this configurationas a virtual image display, the number of discrete components stillresults in a large and cumbersome package. At present, it is extremelydifficult to provide a sufficiently large light source, and to mount thelight source and the polarizers so that the reflective LCSLM is properlyilluminated and can be viewed conveniently.

Thus, it would be beneficial to have reflective LCSLMs with improvedpackaging and lighting so they would be more versatile.

It is a purpose of the present invention to provide new and improvedintegrated electro-optic packaging for reflective spatial lightmodulators.

It is another purpose of the present invention to provide new andimproved integrated electro-optic packaging for reflective spatial lightmodulators utilizing improved light sources.

It is still another purpose of the present invention to provide new andimproved integrated electro-optic packaging for reflective spatial lightmodulators which are useful in forming a virtual image.

It is a further purpose of the present invention to provide new andimproved integrated electro-optic packaging for reflective spatial lightmodulators which is small and compact enough to be utilized in portableelectronic equipment.

It is a still further purpose of the present invention to provide newand improved integrated electro-optic packaging for reflective spatiallight modulators which requires a sufficiently small amount of power tobe utilized in portable electronic equipment.

It is yet another purpose of the present invention to provide new andimproved integrated electro-optic packaging for reflective spatial lightmodulators which includes molded components that are easily andinexpensively fabricated and assembled.

SUMMARY OF THE INVENTION

The above described problems and others are at least partially solvedand the above purposes and others are realized in an integratedelectro-optic package for reflective spatial light modulators includingan array of reflective spatial light modulator pixels formed on asubstrate with each pixel including a control circuit formed in thesubstrate, each control circuit including control terminals adjacent anouter edge of the substrate, a mirror positioned on the substrate inoverlying relationship to the control circuit, and a layer of lightmodulating material positioned in overlying relationship to the mirrorso that light passing through the light modulating material is reflectedback through the light modulating material.

The package further includes a light polarizing layer positioned inoverlying relationship to the array of reflective spatial lightmodulator pixels. An optically clear support is positioned to retain thearray and the light polarizing layer and to provide electricalconnections to the array.

A light source is mounted in the optically clear support and positionedin overlying relationship to the array with the light source spaced fromthe array, so that light from the light source passes through thepolarizing layer, substantially evenly illuminates the array and allowspassage of reflected light from the array through the polarizing layerand the optically clear support.

A diffuser is mounted in overlying and spaced relationship to theoptically clear support to form an image plane for reflected light fromthe array of reflective spatial light modulator pixels which has passedthrough the polarizing layer and the optically clear support.

The above described problems and others are at least partially solvedand the above purposes and others are further realized in a method offabricating an integrated electro-optic package for reflective spatiallight modulators including providing an optically clear support by someconvenient method, such as molding or the like. The optically clearsupport includes a light source, a polarizing layer and a diffuser toprovide an image, as well as electrical leads positioned to connect tothe reflective spatial light modulators and provide an externalelectrical connection thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings:

FIG. 1 is a simplified and enlarged sectional view of a reflectiveliquid crystal spatial light modulator stack;

FIG. 2 is a semi-schematic perspective view for illustrating theoperation of the reflective liquid crystal spatial light modulatorstack;

FIG. 3 is a sectional view of an integrated electro-optic package,including a reflective liquid crystal spatial light modulators stack,embodying the present invention;

FIG. 4 is a simplified schematic view generally illustrating dual imagemanifestation apparatus utilizing two of the integrated electro-opticpackages illustrated in FIG. 3;

FIG. 5 is a perspective view of the dual image manifestation apparatusillustrated in FIG. 4; and

FIGS. 6, 7 and 8 illustrate a front view, side elevational view, and topplan, respectively, of image manifestation apparatus utilizing theintegrated electro-optic package illustrated in FIG. 3; and

FIG. 9 is a 4× magnified view in side elevation of the apparatus of FIG.8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring specifically to FIG. 1, a simplified and enlarged sectionalview of a reflective liquid crystal spatial light modulator (LCSLM)stack 10 is illustrated. Stack 10 includes a substrate 11 formed of anyconvenient semiconductor material, such as silicon, silicon carbide,gallium arsenide, etc. in which integrated electronic circuits can beformed. As will be explained in more detail presently, the integratedelectronic circuits include one driver circuit and associated addressingand switching circuitry for each LCSLM pixel formed in stack 10. Aplurality of bond or terminal pads 12 are formed adjacent the edges ofsubstrate 11 and are in electrical communication with the integratedelectronic circuits so that individual addressing of the electroniccircuits is possible.

A two dimensional array of reflective metal pads 15 are formed on theupper surface of substrate 11, which metal pads 15 each define areflective LCSLM. In the present embodiment, metal pads 15 are made ofaluminum or any metal that can be conveniently patterned on the surfaceof substrate 11 and which will reflect light impinging thereon. Eachmetal pad of the plurality of metal pads 15 is electrically connected toa driver circuit and addressing and switching circuitry so as to formone contact for activating the liquid crystal material in the spaceabove metal pad 15, forming a pixel.

In this embodiment, metal pads are formed in rows and columns and theaddressing and switching circuitry (not shown) includes row and columnelectrical buses and electronic switches coupled to metal pads 15 sothat each metal pad 15 can be individually addressed. The row and columnelectrical buses are electrically connected to the plurality of bond orterminal pads 12 formed adjacent the edges of substrate 11 for externalcommunication (addressing and controlling) with individual metal pads15. Further, it should be noted that metal pads 15 along with anydriving, addressing and switching circuitry is formed in substrate 11and coupled to the plurality of bond or terminal pads 12 with pixelsdefined and formed thereabove.

A generally tubular glass spacer 20 is fixedly attached to the uppersurface of substrate 11 by any convenient means, such as adhesive,chemical bonding, growing and etching layers, etc. It will of course beunderstood that spacer 20 could be formed in a variety of otherembodiments and the present structure is illustrated only for purposesof this explanation. Spacer 20 has an inner opening 21 definedtherethrough with sufficient size to encircle the two dimensional arrayof reflective metal pads 15. The cavity formed by opening 21 in spacer20 in conjunction with the upper surface of substrate 11 is filled withliquid crystal material 22. Typical examples of liquid crystal materialwhich can be used for this purpose are disclosed in U.S. Pat. No.4,695,650, entitled "Liquid Crystal Compounds and CompositionsContaining Same" issued Sep. 22, 1987 and U.S. Pat. No. 4,835,295,entitled "Ferroelectric Liquid Crystal Compounds and Compositions",issued May 30, 1989.

A glass window 25 has a layer 24 of transparent electrically conductivematerial, such as indium-tin-oxide (ITO) or the like, formed thereon todefine a second contact, which, in conjunction with metal pads 15 andliquid crystal material 22 form a complete two dimensional array ofLCSLMs. Glass window 25 is fixedly attached to the upper surface ofglass spacer 20 so that electrically conductive material layer 24 on thelower surface thereof is in contact with liquid material 22 and liquidmaterial 22 is contained within the cavity defined by the upper surfaceof substrate 11, inner opening of spacer 20 and glass window 25. It willbe apparent to those skilled in the art that electrically conductivematerial layer 24 can be formed in a separate or discrete layer that issimply positioned on glass spacer 20 and partially sandwichedtherebetween during assembly.

Electrically conductive material layer 24 is a common second electricalconnection for each pixel defined by metal pads 15 and is connected by aconductive lead to a bond pad 26 adjacent the outer edges of glassspacer 20. Bond pad 26 is then electrically connected to a bond pad 27on substrate 11 by any convenient means, such as wire bond 28, a feedthrough connector in the edges of glass spacer 20 (not shown), etc. Bondpad 27 is adapted to have applied thereto a common potential, such asground or some fixed voltage, which in cooperation with variouspotentials applied to metal pads 15 turn ON, turn OFF, and reset (ifnecessary) each LCSLM in each pixel.

It will be understood that various liquid crystal and ferroelectricliquid crystal material can be provided which will operate in differentmodes in response to different signals or potentials applied thereto.Reflective LCSLMs can be provided, for example, that: rotate thepolarization of light impinging thereon when a predetermined potentialis applied thereacross and do not rotate the polarization when thepotential is removed; rotate the polarization of light impinging thereonwhen no potential is applied thereacross and do not rotate thepolarization when a predetermined potential is applied; rotate thepolarization of light impinging thereon when a first predeterminedpotential is applied thereacross and do not rotate the polarization whena second (lower or higher) potential is applied; etc. Further, commonnematic liquid crystal spatial light modulators do not have a memory anddo not have to be reset after each application of a potential, butferroelectric liquid crystal material has a memory and, at least in someapplications, ferroelectric liquid crystal spatial light modulators mayrequire a reset (or other modifying) signal between normal switchingsignals. Generally, the term "activate" or "activated" will be used toindicate that a signal or signals are being applied to or removed from apixel to cause the pixel to change, regardless of the mode of operation,so as to produce a desired result, which desired result will beapparent.

Glass window 25 completes reflective LCSLM stack 10 which includes a twodimensional array of reflective liquid crystal pixel elements, each ofwhich are individually addressable through bond pads 12. To turn a pixelON a potential must be applied between the upper and lower contacts forthat specific pixel. With no potential applied, the pixel is normally inan OFF condition. Glass plate 25 defines a light input and light outputfor each of the pixels in the two dimensional array of reflectiveLCSLMs. While the present embodiment is explained using liquid crystalmaterial in the pixels, it should be understood that other types ofspatial light modulators might be utilized in the pixels, including, forexample, other types of light modulating liquid or solid material,mirrors or other reflective material, etc.

Referring now to FIG. 2, the operation of reflective LCSLM stack 10 isbriefly explained. A light source 30 is provided, which may be any lightemitting device capable of providing sufficient light for the operationexplained. Light from source 30 is diffused in a plate 31 and polarizedin a second plate 32 before illuminating stack 10. Diffusing plate 31 isprovided to spread the light from source 30 over stack 10. Polarizingplate 32 polarizes the light into a vertical polarization, for example,prior to the light impinging on stack 10.

The liquid crystal, for example ferroelectric liquid crystal material,in stack 10 rotates the polarization of light passing therethrough whenin the activated condition (this operating mode is used only forpurposes of this explanation), just as in a standard twisted nematicliquid crystal display. Thus, light passing through glass plate 25 andliquid crystal material 22 and reflected from pads 15 back throughliquid crystal material 22 and glass plate 25 gets a 90° polarizationrotation in each pixel that is activated. For all pixels in the arraythat are not activated the light passing therethrough is not changed inpolarization.

An analyzing polarization plate 35 is positioned so that light reflectedthrough the plurality of pixels in the array of stack 10 passestherethrough. If, for example, plate 35 is polarized horizontally alllight reflected from pixels that are activated, which light is rotated90° in polarization, will pass through plate 35, while light reflectedfrom pixels which are not activated and which is not rotated inpolarization will be blocked. If plate 35 is vertically polarized, thesame as plate 32, light from pixels which are not activated will passtherethrough and light from pixels which are activated will be blocked.It will be understood that pixels which are constructed to operate inany other mode, such as those described above, may require differentorientation of plates 32 and 35.

Referring now to FIG. 3, an enlarged sectional view of an integratedelectro-optic package 40 embodying the present invention is illustrated.Package 40 includes reflective LCSLM stack 10, which is illustrated inan even more simplified form for convenience. An optically clear support41 having a cavity 42 formed therein is fabricated by any convenientmeans, such as molding, etching, or the like. As an example of apreferred embodiment, support 41 is molded using any convenientoptically clear plastic, such as optically clear liquid epoxy availableunder a Tradename EPO-TEK 301-2 from EPOXY TECHNOLOGY INC. or a clearepoxy molding compound available under the Tradename HYSOL MG18 fromDexter Corporation. In the preferred embodiment, support 41 is formed ofplastic with a relatively low coefficient of expansion (e.g. 20 ppm orless) so that support 41, substrate 11, glass spacer 20 and glass window25 all have a temperature coefficient of expansion within a range thatallows reasonable temperature cycling of the structure without causingcritical or damaging stresses.

Cavity 42 is formed so that stack 10 can be nestingly positioned thereinwith glass window 25 resting near the lower surface of cavity 42. Apolarizing plate 45 is positioned in cavity 42 between the lower surfacethereof and glass plate 25 so that all light entering or exiting glassplate 25 passes through and is polarized by polarizing plate 45. It willof course be understood that polarizing plate 45 can be a separate,discrete plate positioned in cavity 42 before inserting stack 10, orpolarizing plate 45 can be deposited on the surface of glass plate 25 oron the lower surface of cavity 42.

One or more light sources 46 are positioned on the lower surface ofsupport 41 opposite polarizing plate 45. Light sources 46 can include asingle light emitting diode (LED) or several diodes positioned so as tosubstantially uniformly illuminate stack 10. For example, currentlyknown GaN LEDs are capable of producing output power of approximately 40mA and 2 mW, which translates into an output power of approximately 11lumens/watt. While the GaN LEDs are only capable of producing blue toblue/green light at the present time, other LEDs are available forproducing other colors, e.g. GaP for green, AlGaAs for producing red orInGaP for producing red, etc. In this embodiment, for example, threeLEDs (a red, a green and a blue LED) are provided in optically clearsupport 41 and are alternately activated to form three different lightsources 46, each of which fully and uniformly illuminates stack 10 atdifferent times. By activating each LCSLM (pixel) in stack 10 inaccordance with the amount of each color (red, green, or blue) requiredin each pixel during the time that that color LED is activated, acomplete and full color image is produced for each cycle of the threeLEDs. It will of course be understood that more than one LED of eachcolor can be utilized if more than one is required to provide full anduniform illumination.

In this specific embodiment, light sources 46 are embedded in opticallyclear support 41 during the molding process and a patterned transparentconductive layer 47, patterned electrical leads, or imbedded electricalleads are provided on the lower surface of optically clear support 41 toprovide electrical connections to light sources 46. Layer 47 extendsoutwardly to the edges of optically clear support 41 where it acts asexternal electrical contacts for light sources 46. Also, a plurality ofgenerally L-shaped leads 48 are formed in support 41 so as toelectrically engage bond pads 12 and 27 of substrate 11 at one endthereof and so that the other end extends to an outer surface of support41 and forms external electrical terminals for the driver circuits andthe switching and address circuitry formed in substrate 11.

A housing 50 is provided which includes an upper cavity 51 and a lowercavity 52. Housing 50 is formed of optically clear material, such asplastic, and in this preferred embodiment is molded by some convenientprocess, such as injection or thermal set molding. For example, housing50 is molded using any convenient optically clear plastic, such asoptically clear liquid epoxy available under a Tradename EPO-TEK 301-2from EPOXY TECHNOLOGY INC. or a clear epoxy molding compound availableunder the Tradename HYSOL MG18 from Dexter Corporation. In the preferredembodiment, housing 50 is formed of a plastic with an index ofrefraction which substantially matches the index of refraction ofsupport 41 and a coefficient of expansion (e.g. 20 ppm or less) whichalso matches that of support 41.

Upper cavity 51 of housing 50 is formed to nestingly receive opticallyclear support 41 therein with the lower surface of support 41 inabutting engagement with a lower surface of cavity 51. A plurality ofexternal leads 55 are molded into housing 50 so as to extend into cavity51 and electrically engage the external terminal ends of leads 48 and toextend outwardly beyond the outer surface of housing 50 and formmounting and/or external electrical connections for integratedelectro-optic package 40. Leads 48 and leads 55 can be formed initiallyas lead frames and molded into support 41 and housing 50, respectively.

Lower cavity 52 is formed to receive a diffuser 60 therein, whichdiffuser 60 forms an image plane for light emitted from stack 10. Also,some additional optical elements may be positioned in lower cavity 52between the inner surface of cavity 52 and diffuser 60, especially ifthe distance between diffuser 60 and polarizing plate 45 is great enoughto allow too much spreading of the reflected light. Such additionaloptical elements can provide additional magnification and/or partialcollimation prior to the light impinging upon diffuser 60.

Generally, diffuser 60 is formed as an optical lens which is removeablyand/or adjustably mounted in cavity 52. In the present specificembodiment, diffuser 60 is formed in the shape of a disk with externalthreads on the outer periphery thereof, which threads are threadidlyengaged in internal threads on the inner surface of cavity 52. Thus,diffuser 60 can be easily and quickly moved axially relative to stack 10to provide focusing of the image formed on diffuser 60. It should beunderstood that the diffusion required to produce a real image from thelight reflected by the array of LCSLMs can be provided by a diffusionelement positioned between polarizing plate 45 and light source 46 (notshown), or, in some applications, by a diffusion material positioned onthe surfaces of metal plates 15, or some combination of the above.

Lower cavity 52 may be further formed to receive, after receivingdiffuser 60, single or multiple optical elements therein, such asrefractive or diffractive lenses, diffusers, filters, etc. Theadditional optical elements can be formed separately from diffuser 60 oras a single unit with diffuser 60. Also, it will be understood thatdiffuser 60 and/or extra optical elements can be mounted in lower cavity52 by threaded engagement (as illustrated) or by any other convenientmeans, such as "snap-in" or frictional engagement.

Thus, a new and improved integrated electro-optic package for reflectiveSLMs is disclosed which is relatively easy and inexpensive tomanufacture. The package ruggedly mounts the various optical componentswhile conveniently integrating electrical connections to the componentsand providing external connections thereto. Further, light sources,polarizers and a diffuser are conveniently integrated into a smallcompact package which is easily integrated into portable electronicequipment. By using LEDs for the light source, the size of the packageis further reduced and the electrical power required is also minimized.Also, by using multicolored LEDs images with partial or full color canbe formed.

Two different possible applications for integrated electro-optic package40 are incorporated into a portable electronic device including dualimage manifestation apparatus 100, a simplified schematic view of whichis illustrated in FIG. 4. Dual image manifestation apparatus 100includes first image manifestation apparatus 112 constructed to providea large virtual image and second image manifestation apparatus 114constructed to provide a direct view image. Apparatus 112 includes areal image generator 115 affixed in overlying relationship to an opticalinput of an optical waveguide 116. An optical output of opticalwaveguide 116 is positioned to be externally available and has a lenssystem, represented by a single lens 117, affixed thereover.

Image generator 115 includes, for example, integrated electro-opticpackage 40 (as illustrated in FIG. 3) mounted on a printed circuit board113 and driven by data processing circuits (not shown), also mounted onprinted circuit board 113. The data processing circuits include, forexample, logic and switching circuit arrays for controlling each pixelin the SLM array of image generator 115. The data processing circuitsinclude, in addition to or instead of the logic and switching arrays, amicroprocessor or similar circuitry for processing input signals toproduce a desired real image on the diffuser of image generator 115.

In this specific embodiment the pixels are formed in a regular,addressable pattern of rows and columns and, by addressing specificpixels by row and column in a well known manner, the specific pixels areactivated to produce a real image on the diffuser. Digital or analogdata is received at an input terminal and converted by data processingcircuits into signals capable of activating selected LCDs to generatethe predetermined real image.

As the technology reduces the size of package 115, greater magnificationand smaller lens systems are required. Reducing the size of the lenseswhile increasing the magnification results in greatly limiting the fieldof view, substantially reducing eye relief and reducing the workingdistance of the lens system. Generally, optical waveguide 116 includesone or more optical elements 118 and 119, which may be Fresnel lenses,reflective elements, refractive elements, diffractive elements, etc.Elements 118 and 119 may provide some magnification and/or may reducevarious types of distortion. Lens system 117 is mounted so as to receivethe image from optical waveguide 116, magnify it an additionalpredetermined amount and create an aperture within which a virtual imageis viewed. In the present embodiment, optical waveguide 116 and lenssystem 117 magnify the image a total of approximately twenty times.Generally, a magnification greater than ten (10×) is required to magnifythe real image generated by image generator 115 sufficiently to beperceived by a human eye.

It will of course be understood that lens system 117 may be adjustablefor focus and additional magnification, if desired, or may be fixed in ahousing for simplicity. Because the image received by lens system 117from optical waveguide 116 is much larger than the image at imagegenerator 115, lens system 117 may not be required to provide the entiremagnification and, therefore, is constructed larger and with lessmagnification. Because of this larger size, the lens system has a largerfield of view and a greater working distance, which in turn providesbetter eye relief.

Here it should be understood that the virtual image viewed by theoperator through lens system 117 is relatively large (e.g. 8.5"×11") andappears to the operator to be several feet behind dual imagemanifestation apparatus 100. Because of the size of the virtual imageproduced by image manifestation apparatus 112, a large variety ofalphanumeric and/or graphic images can be easily and convenientlyviewed. Further, image manifestation apparatus 112 is very small andcompact so that it can easily be incorporated into portable electronicdevices, such as pagers, two-way radios, cellular telephones, databanks, etc., without substantially effecting the size or powerrequirements.

Second image manifestation apparatus 114 constructed to provide a directview image includes an image generator 120, which includes integratedelectro-optic package 40 (as illustrated in FIG. 3) similar to imagegenerator 115, an optical waveguide 122 an optical element 124 and adirect view screen 125. Optical waveguide 122 may image the output ofimage generator 120 onto screen 125. Image generator 120 is mounted inoverlying relationship on an optical input to optical waveguide 122. Theimage from image generator 120 is reflected and/or otherwise directed byan optical element 121 onto optical element 124. While element 124 isillustrated as a separate element, it will be understood that it couldbe incorporated as a portion of optical waveguide 122. Optical element124 can also include a Fresnel lens, or the like, for focusing and/ormagnification if desired. The image from optical element 124 is directedonto screen 125 where it can be directly viewed by the operator.

Image manifestation apparatus 114 provides a direct view image which canbe no larger than screen 125 upon which it is projected. Because of themuch smaller size of the direct view image, the amount of magnificationrequired is much smaller, i.e. less than approximately 10×. Generally,while the direct view image is much smaller than the virtual imageproduced by image manifestation apparatus 112, more light (larger lightsource) is required to generate the direct view image because more lightis required to project the image onto screen 125. However, because thedirect view image is smaller, any message contained in the direct viewimage must be larger in order to be perceived by the operator. Thus,whereas one pixel in the array of image generator 115 produces one pixelin the final virtual image (for example), several pixels in the array ofimage generator 120 operate in conjunction to produce one pixel in thedirect view image on screen 125. Because several pixels produce onepixel, in many instances the higher light requirement may beautomatically resolved. If additional light is required in someapplications, additional LEDs (described above) or higher current andcorrespondingly higher light output may be utilized as the light source,as one example.

Referring specifically to FIG. 5, a perspective view of dual imagemanifestation apparatus 100 in a portable electronic device isillustrated in a typical housing 145. Screen 125 is visible through anopening in the front of housing 145 for the direct viewing of imagesthereon. Also, an aperture is provided in the front of housing 145 toreceive lens system 117 so that the virtual image produced by imagemanifestation apparatus 112 may be readily viewed. A touch pad 146 isoptionally provided on the front surface of housing 145 for controllinga cursor in the virtual image, which cursor may further controldisplayed keyboards and/or other controls. Additional controls 148 areprovided on an upper surface of housing 145 and generally include suchfeatures as an on/off switch, and controls for any electronic devicesconnected thereto.

Video from a receiver or other data source within the portableelectronic device is communicated to either or both image manifestationapparatus 112 and 114 for convenient viewing by the operator. Generally,for example, control signals titles, etc. may appear in the direct viewimage on screen 125 while larger alpha-numeric messages and graphicswill appear in the virtual image at lens system 117. Also, in someapplications, it is envisioned that dual image manifestation apparatus100 may be constructed so that image manifestation apparatus 112 can bephysically separated from image manifestation apparatus 114, along line147 for example, and each can be used separately. In such an embodimentimage manifestation apparatus 112 is a very low power device while imagemanifestation apparatus 114 generally requires more power and will, forexample, generally contain the portable electronic equipment (e.g. acommunication receiver).

FIGS. 6, 7 and 8 illustrate a front view, side elevational view, and topplan, respectively, of another miniature virtual image display 150 inaccordance with the present invention. FIGS. 6, 7 and 8 illustrateminiature virtual image display approximately the actual size to providesome indication as to the extent of the reduction in size achieved bythe present invention. Display 150 includes an integrated electro-opticpackage 155 which includes, in this specific embodiment, 144 pixels by240 pixels. Each pixel is fabricated approximately 20 microns on a sidewith a center-to-center spacing between adjacent diodes of no more than20 microns. In a preferred embodiment, integrated electro-optic package155 produces a luminance less than approximately 15 fL. This very lowluminance is possible because display 150 produces a virtual image.Further, because a very low luminance is required, LEDs and the like maybe utilized as the light source for the SLM stack, which greatly reducesthe size and power requirements. Integrated electro-optic package 155 ismounted on the surface of a driver board 158. An optical system 165 isalso mounted on driver board 158 and magnifies the image approximately20× to produce a virtual image approximately the size of an 8.5"×11"sheet of paper.

Here it should be noted that because of the very small integratedelectro-optic package 155 and the fact that a virtual image is utilized,rather than a direct view display, the overall physical dimensions ofminiature virtual image display 150 are approximately 1.5 inches (3.8cm) wide by 0.75 inches (1.8 cm) high by 1.75 inches (4.6 cm) deep, or atotal volume of approximately 2 cubic inches (32 cm³).

Referring specifically to FIG. 9, a 4× magnified view in side elevationof miniature virtual image display 150 of FIG. 8 is illustrated forclarity. From this view it can be seen that a first optical lens 167 isaffixed directly to housing 50 (see FIG. 3). An optical prism 170 ismounted to reflect the image from a surface 171 and from there through arefractive surface 172. The image is then directed to an optical lens175 having a refractive inlet surface 176 and a refractive outletsurface 177. From lens 175 the image is directed to an optical lens 180having an inlet refractive surface 181 and an outlet refractive surface182. Also, in this embodiment at least one diffractive optical elementis provided on one of the surfaces, e.g. surface 171 and/or surface 176,to correct for aberration and the like. The operator looks into surface182 of lens 180 and sees a large, easily discernible virtual image whichappears to be behind display 150.

It should be noted that in the prior art, pagers and other smallreceivers in which visual displays are desired are especiallyhandicapped by the size of the displays. Generally such displays arelimited to a single short line of text or several digits, and the sizeof the display still dictates the size of the receiver. Utilizing anembodiment of the present invention, a display with several lines oftext to a full page can be incorporated and the size of the receiver orother portable electronic equipment can be substantially reduced.Further, the display is clearer and easier to read and, because itutilizes a virtual display, requires very little power for the operationthereof. In fact, the present display uses much less power than any ofthe direct view displays normally utilized in electronic equipment and,as a result, can be fabricated in much smaller sizes.

Thus a greatly improved portable electronic device with miniaturevirtual image display is disclosed, which incorporates an extremelysmall spatial light modulator array on a semiconductor chip. Because avirtual image display is utilized, the display is constructed very smalland requires very little power. Further, because of the extremely smallsize and power consumption of the virtual image display, it isincorporated into portable electronic equipment without substantiallyeffecting the size or power requirements. The miniature virtual displayprovides a predetermined amount of magnification along with sufficienteye relief and lens working distance to create a comfortable andviewable virtual image. Also, a complete virtual image is produced withno moving parts or power consuming motors and the like. Further, theelectronics provided as a portion of the miniature virtual image displayallows a variety of very small real images to be generated. The verysmall real image is magnified into a large virtual image that is easilyperceived by the operator.

While we have shown and described specific embodiments of the presentinvention, further modifications and improvements will occur to thoseskilled in the art. We desire it to be understood, therefore, that thisinvention is not limited to the particular forms shown and we intend inthe appended claims to cover all modifications that do not depart fromthe spirit and scope of this invention.

What is claimed is:
 1. An integrated electro-optic package forreflective spatial light modulators comprising:an array of reflectivespatial light modulator pixels formed on a substrate with each pixelincluding a control circuit formed in the substrate, each controlcircuit including control terminals adjacent an outer edge of thesubstrate, a mirror positioned on the substrate in overlyingrelationship to the control circuit, and spatial light modulatormaterial positioned in overlying relationship to the mirror so thatlight passing through the spatial light modulator material is reflectedback through the spatial light modulator material; a light polarizinglayer positioned in overlying relationship to the array of reflectivespatial light modulator pixels; a light source mounted in an opticallyclear support positioned in overlying relationship to the array ofreflective spatial light modulator pixels with the light source spacedfrom the array of reflective spatial light modulator pixels, so thatlight from the light source substantially evenly illuminates the arrayof reflective spatial light modulator pixels and allows passage ofreflected light from the array of reflective spatial light modulatorpixels through the optically clear support; and a diffuser mounted inoverlying relationship to the optically clear support to form an imageplane for reflected light from the array of reflective spatial lightmodulator pixels.
 2. An integrated electro-optic package for reflectivespatial light modulators as claimed in claim 1 wherein the opticallyclear support is optically clear plastic.
 3. An integrated electro-opticpackage for reflective spatial light modulators as claimed in claim 2wherein the optically clear plastic has a temperature coefficient ofexpansion that is substantially similar to the array of reflectivespatial light modulator pixels temperature coefficient of expansion. 4.An integrated electro-optic package for reflective spatial lightmodulators as claimed in claim 1 wherein the optically clear support ismolded optically clear plastic.
 5. An integrated electro-optic packagefor reflective spatial light modulators as claimed in claim 1 whereinthe light source includes a plurality of light emitting diodes.
 6. Anintegrated electro-optic package for reflective spatial light modulatorsas claimed in claim 5 wherein the plurality of light emitting diodesincludes at least two diode, each of which emit a different color oflight.
 7. An integrated electro-optic package for reflective spatiallight modulators as claimed in claim 1 wherein the optically clearsupport includes a molded optically clear plastic and the light sourceis a plurality of light emitting diodes embedded in the optically clearplastic.
 8. An integrated electro-optic package for reflective spatiallight modulators as claimed in claim 1 where, in the array of reflectivespatial light modulator pixels, the layer of spatial light modulatormaterial is a continuous layer across the entire array and each controlcircuit for each pixel formed in the substrate includes one contact, thearray further including an optically clear contact positioned on anopposite side of the continuous layer with the one contact and theoptically clear contact defining a pixel within the continuous layer. 9.An integrated electro-optic package for reflective spatial lightmodulators as claimed in claim 8 wherein the spatial light modulatormaterial includes liquid crystal material.
 10. An integratedelectro-optic package for reflective spatial light modulators as claimedin claim 8 wherein the liquid crystal material includes ferroelectricliquid crystal material.
 11. An integrated electro-optic package forreflective spatial light modulators as claimed in claim 8 wherein theoptically clear contact for each pixel is formed in a layer ifindium-tin-oxide deposited in overlying relationship to the continuouslayer of spatial light modulator material.
 12. An integratedelectro-optic package for reflective spatial light modulators as claimedin claim 8 wherein the mirror positioned on the substrate is a polishedpad of metal, one for each pixel, which pad of metal also forms the onecontact included in the control circuit.
 13. An integrated electro-opticpackage for reflective spatial light modulators as claimed in claim 10wherein the polished pad of metal for each pixel is a polished pad ofaluminum.
 14. An integrated electro-optic package for reflective spatiallight modulators as claimed in claim 1 including in addition a housinghaving the light source and the optically clear support mounted therein,with the diffuser being removeably mounted and further mounted for axialmovement toward and away from the optically clear support to providefocusing of images formed on the diffuser.
 15. An integratedelectro-optic package for reflective spatial light modulators as claimedin claim 1 including in addition a housing including leads formedtherein so as to be in electrical contact with the control terminalsadjacent an outer edge of the substrate of each control circuit and theleads further extend to an external portion of the housing to formexternal contacts for the control circuits.
 16. An integratedelectro-optic package for reflective spatial light modulators as claimedin claim 15 wherein the housing is molded and the leads are a leadframemolded into the housing.
 17. An integrated electro-optic package forreflective liquid crystal spatial light modulators comprising:areflective liquid crystal spatial light modulator stack including asubstrate with a plurality of control circuits formed therein, eachcontrol circuit including control terminals adjacent an outer edge ofthe substrate and an electrical contact mirror positioned on thesubstrate, each electrical contact mirror defining a pixel and a firstelectrical contact for the pixel, a layer of liquid crystal spatiallight modulator material positioned in overlying relationship to theelectrical contact mirrors so that light passing through the liquidcrystal spatial light modulator material is reflected back through theliquid crystal spatial light modulator material, and an electricallyconductive optically transparent layer of material positioned on anopposite surface of the liquid crystal spatial light modulator materialto form a second electrical contact for each pixel; a light polarizinglayer positioned in overlying relationship to the electricallyconductive optically transparent layer of material; a light sourcemounted in an optically clear support positioned in overlyingrelationship to the reflective liquid crystal spatial light modulatorstack with the light source spaced from the reflective liquid crystalspatial light modulator stack, so that light from the light sourcesubstantially evenly illuminates the reflective liquid crystal spatiallight modulator stack and allows passage of reflected light from thereflective liquid crystal spatial light modulator stack through theoptically clear support; and a diffuser mounted in overlying and spacedrelationship to the optically clear support to form an image plane forreflected light from the reflective liquid crystal spatial lightmodulator stack.
 18. An integrated electro-optic package for reflectiveliquid crystal spatial light modulators as claimed in claim 17 whereinthe layer of liquid crystal spatial light modulator material iscontained within a closed cavity having internal opposed flat surfaces,the electrical contact mirrors are affixed to one of the internalsurfaces and the electrically conductive optically transparent layer isaffixed to the other of the internal surfaces.
 19. An integratedelectro-optic package for reflective liquid crystal spatial lightmodulators as claimed in claim 18 wherein the closed cavity is definedby a surface of the substrate, a spacer affixed to the surface of thesubstrate and a glass plate affixed over the spacer.
 20. An integratedelectro-optic package for reflective liquid crystal spatial lightmodulators comprising:a reflective liquid crystal spatial lightmodulator stack includinga substrate with a plurality of controlcircuits formed therein, each control circuit including controlterminals adjacent an outer edge of the substrate and an electricalcontact mirror positioned on the substrate, each electrical contactmirror defining a pixel and a first electrical contact for the pixel, alayer of liquid crystal spatial light modulator material positioned inoverlying relationship to the electrical contact mirrors so that lightpassing through the liquid crystal spatial light modulator material isreflected back through the liquid crystal spatial light modulatormaterial, an electrically conductive optically transparent layer ofmaterial positioned on an opposite surface of the liquid crystal spatiallight modulator material to form a second electrical contact for eachpixel, and the layer of liquid crystal spatial light modulator materialbeing contained within a closed cavity having internal opposed flatsurfaces and defined by a surface of the substrate, a spacer affixed tothe surface of the substrate and a glass plate affixed over the spacerwith the electrical contact mirrors affixed to one of the internalsurfaces and the electrically conductive optically transparent layeraffixed to the other of the internal surfaces; an optically clearsupport having defined therein a cavity formed to receive the reflectiveliquid crystal spatial light modulator stack in nesting engagement, theoptically clear support further including a plurality of electricalleads each formed therein so as to provide a first contact in the cavityand a second contact at an external surface of the optically clearsupport; a light polarizing layer positioned in the cavity of theoptically clear support; the reflective liquid crystal spatial lightmodulator stack being nestingly positioned in the cavity so that thepolarizing layer is positioned in overlying relationship to theelectrically conductive optically transparent layer of material; a lightsource mounted in the optically clear support and positioned inoverlying relationship to the reflective liquid crystal spatial lightmodulator stack with the light source spaced from the reflective liquidcrystal spatial light modulator stack, so that light from the lightsource passes through the polarizing layer, substantially evenlyilluminates the reflective liquid crystal spatial light modulator stack,and allows passage of reflected light from the reflective liquid crystalspatial light modulator stack through the polarizing layer and theoptically clear support; and a diffuser mounted in overlying and spacedrelationship to the optically clear support to form an image plane forreflected light from the reflective liquid crystal spatial lightmodulator stack which passes through the polarizing layer and theoptically clear support.
 21. A method of fabricating an integratedelectro-optic package for reflective spatial light modulators comprisingthe steps of:providing a stack including a plurality of reflectivespatial light modulators formed in a two dimensional array on asemiconductor substrate with drive electronics formed in the substratefor each spatial light modulator of the array of spatial lightmodulators and control terminals for the drive electronics positionedadjacent outer edges of the substrate, the stack further including alight transparent surface defining a light input and light output foreach of the spatial light modulators in the two dimensional array ofreflective spatial light modulators; forming an optically clear supporthaving defined therein a cavity formed to receive the reflective spatiallight modulator stack in nesting engagement with a lower surface of thecavity substantially parallel with and adjacent to the light transparentsurface of the stack, the optically clear support further being formedto include a plurality of electrical leads each positioned therein so asto provide a first contact in the cavity and a second, electricallycoupled contact at an external surface of the optically clear support;providing a light polarizing layer and positioning the polarizing layerin the cavity of the optically clear support; positioning the stacknestingly in the cavity so that the polarizing layer is positioned inoverlying relationship and adjacent to the light transparent surface ofthe stack; mounting a light source in the optically clear support andpositioning the light source in overlying relationship to the lighttransparent surface of the stack with the light source spaced from thelight transparent surface of the stack, so that light from the lightsource passes through the polarizing layer, substantially evenlyilluminates the light transparent surface of the stack, and allowspassage of reflected light from the light transparent surface of thestack through the polarizing layer and the optically clear support; anddiffusing light reflected from the stack to form an image.
 22. A methodof fabricating an integrated electro-optic package for reflectivespatial light modulators as claimed in claim 21 wherein the step ofdiffusing includes mounting a diffuser in overlying relationship to theoptically clear support to form an image plane for light reflected fromthe stack and passing through the polarizing layer and the opticallyclear support.
 23. A method of fabricating an integrated electro-opticpackage for reflective spatial light modulators as claimed in claim 21wherein the step of forming an optically clear support includes moldingthe optically clear support from plastic.
 24. A method of fabricating anintegrated electro-optic package for reflective spatial light modulatorsas claimed in claim 23 wherein the step of molding the optically clearsupport from plastic includes a step of molding a leadframe into theplastic to form the plurality of electrical leads.
 25. A method offabricating an integrated electro-optic package for reflective spatiallight modulators as claimed in claim 24 wherein the step of molding theoptically clear support from plastic and the step of mounting a lightsource in the optically clear support include forming the opticallyclear support with a second surface spaced from the lower surface of thecavity and on a side opposite thereto and embedding at least one lightemitting diode into the second surface.